Good Day,
I have a carport canopy design where the bottom section of the canopy column is concrete and the top is steel. See attached sketch depicting what is required. I need to transfer a 50kNm moment from the steel "star" column on top to the concrete column below. There will be a baseplate...
For a flat slab, I have been trying to find some info on deflection vs time, for example a graph.
Given a constant load, what is the typical rate of deflection? I know it depends on MANY factors, humidity, time of 1st loading, rebar etc.
But a general estimate. Say the maximum a slab will ever...
I have a case where the reinforcement bars in a column do not protrude into the slab above, bars were fixed short. The column is cast.
No, If a design the column as pinned at the top, I still need to provide minimum restraint so that column top cannot move laterally and remains fixed to slab...
Say you have a step in a flat slab, for example a 150mm step in the soffit and top of slab. Is there any reason why one could not step a continuous slab if the following criteria are met:
* You crank bars so that you have one continuous bar across the step
* The minimum radius of the bends in...
Hi,
This has been discussed before, but I have a few new questions.
I have a waffle (coffer) slab, continuous in one direction and single span in other. The single span is 10.25m and the continuous spans are 8.5.
It is for office floors, so quite light loading. I am using a 450 thick waffle...
Hi,
I would like to know what tensile force the following welded connection can carry. A 16mm bar (500MPa yield strength) welded to a 20mm thick plate (350MPa).
The connection was welded as follows:
A 20mm diameter hole drilled in plate, bar pushed through and plug welded on bottom. The gap...
I have a situation where a concrete column is already built. I now need a flat slab at mid height of this column, to be supported by this column. In effect the column should be cast to slab soffit, the slab then cast, then column above cast. The slab was added later after column was already...
I have a project where we need to construct a 26m beam, in situ. precast T beams wont work as we cannot get a crane access to lift them.
I will be able to provide a back span of about 12m which will help a lot, can probably get away with a 1.8m deep beam, 850mm wide.
I have never designed or...
Good evening,
I have previously posted on minimum moment a column supporting a slab should be designed for. In the case of a column supporting a long span beam (16m) this moment becomes incredibly large if taken from a finite element analysis.
Rapt, one of the members, previously posted that...
I have read an earlier thread on the topic, but the matter remains unclear.
Codes specify that the main tension rebar crossing a shear plane considered must be fully anchored (developed) either side of this plane. My understanding is that this is to keep the concrete together so that it can...
This is a simple question but I cant find a clear answer in the codes we use:
If you have a concrete column supporting a slab, but also a downstand beam that ties into one face of the column at the top, can you use the column base to slab- or beam soffit as the column clear height?
In this...
Good Day,
Has anyone used a concrete beam and column frame structure, infilled with brickwork, as a lateral bracing structure in a building?
It is common to have a concrete column and beam frame work to form stair and hoist shafts and to then infill it with brickwork. To what extent can one...
I have a edge column with following end conditions, what you use in design:
Bottom: 550mm square columns with starter bars that were cast into a 1000mm diameter pile. The pile designer says that the pile would be able to carry 50kNm in bending.
Top: 550mm square column tied into a 550mm deep...
Foundations to columns have been cast anf column starter bars are in. The height of the column must now increase but the size must stay the same. So the steel in the column must increase, and I must add another 4 20mm bars. The column starter bars were cast into the pile foundation so we cannot...
Question: I designed a concrete retaining wall, the base is 500mm thick. Now my design usually allows for a safety factor of 1.5 against slip/sliding. In this design a very small force is used as passive pressure onto the front toe of the 500 thick wall base.
If the base is excavated into...
Hi Guys,
Would like to hear your opinions on use of wet to dry epoxy to bond new concrete to existing.
When for example you are casting a suspended slab, the pour is too big to do in one hit, now you just let the concrete run off at 45 degrees at the line where you want the construction joint...
It is quite normal to use a lower grade/class concrete in foundations, such as 25MPa. But for columns often higher strength concrete is used such as 40MPa.
My question is, if you have a 40MPa column supported on a 25MPa spread footing, will it be okay.
According to BS 8110 you can use 0.67 of...
I am a structural engineer working on a project where we need to confirm soils used to back fill behind a wall are okay for building a hardstand on.
The material is sandstone mixed with some clayey material. We have had the soils tested by a laboratory, who stabilised the soild with 4% cement...
I am doing a report on a masonry building with significant cracking on walls.
In my view most cracking is as a result of foundation settlement. On one specific wall there is a continuous crack from top window corner to top window corner. I have read that this indicates settlement, what would be...
If a concrete beam is designed as pinned at the supports where it fixes to the columns, what is the minimum moment that one should allow to be transferred to the column? If it is designed as simply supported, but some nominal reinforcement is fixed to the top corners of the beam and bend down...
